In recent years, there have been proposed various methods of treating and recycling plastic waste, and further, parts thereof have been practically employed. As a potent one of such methods of treating plastic waste, there has been proposed an apparatus and method involving gasifying the plastic waste by heating chips of the plastic waste in the presence of a decomposition catalyst of titanium oxide known as a photocatalyst (see Patent Literatures 1 and 2).
Further, catalysts used for decomposition treatment of the plastic waste chips have been variously studied (Patent Literatures 3 to 6).
The inventors of the present invention have provided excellent methods of treating plastic waste by using titanium oxide granules each having a structure entirely different from those of related-art titanium oxide (see Patent Literatures 7 and 8).
In addition, there have been reported several metal oxide-containing titanium oxide compounds (see Patent Literatures 9 to 11). However, Patent Literatures 9 to 11 do not disclose or suggest “substantially spherical titanium oxide granules having a metal supported thereon.”
Meanwhile, regarding the prevention of secondary infection caused by infectious medical waste discharged from hospitals, dialysis facilities, and the like, a guideline specifying the method of treating waste of that kind was issued from the Ministry of Health and Welfare on Nov. 7, 1989, and was enforced on Apr. 1, 1990. The guideline orders the hospitals, dialysis facilities, and the like to conduct in-house sterilization treatment of the medical waste, in principle.
In this regard, there is an increasing demand for the development of a decomposition method, a decomposition apparatus, and a decomposition system each of which enables the treatment of plastic waste, in particular infectious medical waste containing polyvinyl chloride, in facilities such as hospitals and clinics safely and rapidly without the need of a large scale apparatus.